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allowing more starting torque with less
amperage while the machine is accelerating
to full high spin speed.
The wash contactors (KMP and KML) are
mechanically interlocked together to prevent
them from ever engaging simultaneously.
Low Spin and Shorting (KM2 and KM3) are
also mechanically interlocked.
Installed across contacts of the wash
contactors (KMP and KML) are RC (resistor-
capacitor) networks identified as Z1 and Z2.
These function as EMI filters and reduce
arcing of the contacts when the contactors
are engaged and disengaged. If EMI interfer-
ence-related control board problems are
encountered, the RC networks should be
checked.
CURRENT OVERLOAD PROTECTORS
On many MFS models, current overload
protectors are installed piggybacked to the
input side of the contactors. One current
overload protector will be installed on the
input of the contactors that supply current to
the wash motor (KMP, KML, and KM1) and is
identified as FA 1. A second current overload
protector is installed on the inputs of the
contactors that supply current to the spin
motor (KM2, KM3, and KM4) and is identified
as FA2. Consult the wiring diagram that
comes with the machine for proper setting of
the current overload protector.
The current overload protector is connected
as a normally closed switch in series with
power to the solenoids of the contactors in
which it is connected. If an overcurrent is
detected, the switch will open removing
power from the contactor solenoids, prevent-
ing them from engaging until the current
overload resets. If a current overload protec-
tor opens during a cycle, the "Overload Fault"
code will appear on the control board display.
If a current overload protector is open at the
start of a cycle, the "Close Door Press Start"
code will appear on the control board display.
CIRCUIT BREAKER
The entire contactor set is protected by a
separate circuit breaker and is identified as
FA. This circuit breaker is installed in the 3
phase line that feeds all the inputs of the
contactors and is located in the same area as
the contactors. If the circuit breaker is open
(off}, there will be no motor function, regard-
less of whether the computer display indi-
cates a cycle is in progress, or if the
contactors engage and disengage in a nor-
mal manner.
FUSES
Each machine is protected by fuses installed
in the lines that feed the controls of the
machine. The input (primary) of the control
transformer is fused on both the Line 1 and
Line 2 sides, as well as fused with one fuse
on the output (secondary) side of the control
transformer.
On most machines, provision is made to
supply a 208-240 volt power source for use
with external chemical supply injection
systems. These connections are also fused
with a separate fuse in each line of this 208-
240 volt supply.
All fuses used in MFS machines are 5mm X
20mm metric fuses. Replace fuses with exact
replacement only. Consult the wiring dia-
gram that comes with the machine for proper
fuse sizes. Never use oversized fuses.
CONTROL TRANSFORMER
The controls are isolated from the 3 phase
line by the control transformer. The
transforme(s primary (input) is connected to
two of the three 3 phase lines. The second-
ary (output) is connected to the controls and
the frame of the machine. The transformer is
rated at 250 VAC.
As connected, the transformer has a 1: 1 ratio
with the secondary voltage typically measur-
ing approximately the same as the incoming
3 phase line voltage.
16009607
Section 2. Service Procedures
©1999 Maytag Appliances Sales Company
2-5
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